Devices and methods for treating bone

ABSTRACT

A device is disclosed for reducing a vertebral compression fracture, comprising a superior end plate and an inferior end plate disposed along a vertical axis. The superior end plate and the inferior end plate are slidably separable in a vertical direction along the vertical axis. An interior chamber is provided in fluid communication with a port extending from an exterior to the interior chamber. The device is deployable within a vertebral body and expandable within the vertebral body by injecting a flowable material into the interior chamber thereby displacing the superior and inferior end plates along the vertical axis.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent Application is a continuation application claiming priorityto U.S. patent application Ser. No. 12/201,112, filed on Aug. 29, 2008,the entire contents of which are incorporated by reference.

FIELD OF THE INVENTION

The present invention generally relates to devices and methods fortreating bone. In particular, certain embodiments are directed tominimally invasive distraction and support devices and devices andmethods to treat bone fractures.

BACKGROUND OF THE INVENTION

A minimally invasive distraction and support device and method wouldhave significant application in orthopaedic surgical procedures,including acute and elective procedures to treat bone fractures anddegenerative changes of the skeletal system and including vertebralcompression fractures, interbody fusion, vertebral disc augmentation orreplacement, and other compression fractures and/or non-orthopaedicsurgical procedures.

A vertebral compression fracture is a crushing injury to one or morevertebrae. Vertebral fractures are generally associated withosteoporosis (the “brittle bone” disease), metastasis, and/or trauma.Osteoporosis reduces bone density, thereby weakening bones andpredisposing them to fracture.

The osteoporosis-weakened bones can collapse during normal activity. Insevere cases of osteoporosis, actions as simple as bending forward canbe enough to cause a vertebral compression fracture. Vertebralcompression fractures are generally known to be the most common type ofosteoporotic fractures. The mechanism of these fractures is one offlexion with axial compression where even minor events may cause damageto the weak bone. While the fractures may heal without intervention, thecrushed bone may fail to heal adequately. Moreover, if the bones areallowed to heal on their own, the spine will be deformed to the extentthe vertebrae were compressed by the fracture. Spinal deformity may leadto breathing and gastrointestinal complications, and adverse loading ofadjacent vertebrae.

Vertebral fractures happen most frequently at the thoracolumbarjunction, with a relatively normal distribution of fractures around thispoint. Vertebral fractures can permanently alter the shape and strengthof the spine. Commonly, they cause loss of height and a humped back.This disorder (called kyphosis or “dowager's hump”) is an exaggerationof the spinal curve that causes the shoulders to slump forward and thetop of the back to look enlarged and humped. In severe cases, the body'scenter of mass is moved further away from the spine resulting inincreased bending moment on the spine and increased loading ofindividual vertebrae.

Another contributing factor to vertebral fractures is metastaticdisease. When cancer cells spread to the spine, the cancer may causedestruction of part of the vertebra, weakening and predisposing the boneto fracture.

Osteoporosis and metastatic disease are common root causes leading tovertebral fractures, but trauma to healthy vertebrae also causes minorto severe fractures. Such trauma may result from a fall, a forcefuljump, a car accident, or any event that stresses the spine past itsbreaking point. The resulting fractures typically are compressionfractures or burst fractures.

Vertebral fractures can occur without pain. However, they often cause asevere “band-like” pain that radiates from the spine around both sidesof the body. It is commonly believed that the source of acute pain incompression fractures is the result of instability at the fracture site,allowing motion that irritates nerves in and around the vertebrae.

Various instruments and methods for the treatment of compression-typebone fractures and other osteoporotic and/or non-osteoporotic conditionshave been developed. Such methods generally include a series of stepsperformed by a surgeon to correct and stabilize the compressionfracture. A cavity is typically formed in the bone to be treated,followed by the insertion of one or more inflatable balloon-likes deviceinto the bone cavity. Inflation of the balloon-like device into causes acompaction of the cancellous bone and/or bone marrow against the innercortical wall of the bone, thereby resulting in enlargement of the bonecavity and/or reduction of the compression fracture. The balloon-likedevice is then deflated and removed from the bone cavity. Abiocompatible filling material, such as methylmethacrylate cement or asynthetic bone substitute, is sometimes delivered into the bone cavityand allowed to set to a hardened condition to provide internalstructural support to the bone. In theory, inflation of the balloonsrestores vertebral height. However, it is difficult to consistentlyattain meaningful height restoration. It appears the inconsistentresults are due, in part, to the manner in which the balloon expands ina compressible media and the structural orientation of the trabecularbone within the vertebra.

For example, it has been found that expansion of the balloon-like devicecan be difficult to control. Instead, when such a balloon-like device isinflated, expansion occurs along a path of least resistance. As aresult, the direction of compaction of the cancellous bone and/orreduction of the compression fracture is not controllable, and expansionoccurs in multiple directions and along multiple axes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a vertebral body having a compression fracture displacingits superior and anterior edge;

FIG. 2 shows a vertebral body, following treatment of a compressionfracture;

FIG. 3 is a side view of one embodiment of a bone treatment deviceaccording to the invention;

FIG. 4 is a side view of the device of FIG. 3 shown in a collapsedposition;

FIG. 5 is a top view of the device of FIG. 3 shown in an implantedposition within a vertebral body;

FIG. 6 is a side view of another embodiment of a bone treatment deviceaccording to the invention;

FIG. 7 is an end view of another embodiment of a bone treatment deviceaccording to the invention;

FIGS. 8A-B are side and end views, respectively, of another embodimentof a bone treatment device according to the invention;

FIG. 9 is a side view of another embodiment of a bone treatment deviceaccording to the invention;

FIG. 10 is a top view of the device of FIG. 9 shown in an expandedcondition;

FIG. 11 is a side view of an installation gun useable with the device ofFIG. 9;

FIGS. 12A-C are side and end views of another embodiment of a bonetreatment device according to the invention;

FIGS. 13-14 are side views of alternate embodiments of bone treatmentdevices according to the invention;

FIGS. 15A-C are side and end views of another embodiment of a bonetreatment device according to the invention;

FIGS. 16A-B are side views of another embodiment of a bone treatmentdevice shown in first and second positions with respect to a vertebralbody;

FIG. 17 is a perspective view of another embodiment of a bone treatmentdevice according to the invention shown in relation to a vertebral body;

FIG. 18 is a perspective view of another embodiment of a bone treatmentdevice according to the invention;

FIGS. 19A-B are side and end views, respectively, of another embodimentof a bone treatment device;

FIGS. 20A-B are side views of another embodiment of a bone treatmentdevice according to the invention;

FIG. 21 is a perspective view of another embodiment of a bone treatmentdevice according to the invention shown in relation to a vertebral body;

FIGS. 22A-B are side and top views, respectively, of another embodimentof a bone treatment device according to the invention;

FIGS. 23A-B are side perspective views of one embodiment of a cavitycreation device according to the invention;

FIGS. 24A-B are views of another embodiment of a cavity creation deviceaccording to the invention; and

FIG. 25 is a perspective view of another embodiment of a bone treatmentdevice according to the invention shown in relation to a vertebral body.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Embodiments of the present invention are generally directed to devicesand methods for creating a cavity in bone. In particular, certainembodiments are directed to minimally invasive distraction and supportdevices and methods to treat bone fractures.

The devices and methods are generally described by its application tothe vertebral compression fracture. FIG. 1 illustrates two vertebrae 10,12, each with an anterior side 14, a posterior side 16, and lateralsides 18 (only one shown). Vertebra 10 is fully intact, while vertebra12 has a vertebral compression fracture (i.e., the top 20 and bottom 22of the vertebra have been displaced towards each other). Referring toFIG. 2, the vertebral compression fracture of vertebra 12 is shown in areduced or height restored state (i.e., the top 20 and bottom 22 of thevertebra 12 are distracted or displaced back to or near their originalintact positions). It is known that the force required to reduce thevertebral compression fracture can often be rather high.

Referring to FIGS. 3-5, one embodiment of a bone fracture distractiondevice or implant 40 is shown. Device 40 generally comprises a pair ofrigid upper and lower plate members 42, 44 and an anterior end platemember 46 rotatably and linkedly connected to one of the upper or lowerplate members 42, 44. In one variation, anterior plate member 46 isgenerally connected to the distal end of upper plate 42. A posterior endplate 48 may be linkedly connected between both the upper and lowerplates 42, 44 adjacent the posterior end of plates 42, 44. In general,anterior plate 46 may swing or rotate about the distal end of plate 42.Plates 42, 44, 46, and 48 may be generally thin wafer like plate membersand may have varying widths and lengths. As best seen in the top viewshown in FIG. 5, in one embodiment, the size of the plates could have awidth 57 between about 3 mm and about 4 mm wide. Also shown in FIG. 5,according to one aspect, the upper and lower plate members 42, 44 maydefine openings or perforations 59 to facilitate passage or bone cementand/or bone growth therethrough.

A plurality of ratcheting grooves 50 may be provided along a portion ofthe interior of lower plate 44 to ratchetedly engage the free end 52 ofanterior plate 46. In this regard, as the anterior plate 46 is moved orrotated outwards, the free end 52 of anterior plate 46 slidingly engagesthe grooves 50 similar to a ratchet mechanism such that when a downwardforce is applied to upper plate 42, anterior end plate 46 may only movein an outward direction and the ratchet grooves 50 prevent movement offree end 52 in an opposite inward direction. Such a ratchet featurefacilitates distraction and support of a bone fracture as the anteriorend plate 46 is rotated or pushed outward. In the exemplary embodimentdepicted in FIG. 3, end plate 46 is linkedly attached to upper plate 42,however, end plate 46 could alternatively be linkedly connected to lowerplate 44 and a similar ratchet like interface may be provided on theupper plate.

As is illustrated in FIG. 4, the device 40 may be positioned in acollapsed state with the upper plate 42, lower plate 44, and anteriorand posterior plates 46, 48 folded generally flat with the free end 52of anterior plate 46 positioned adjacent the posterior end of device 40.In this regard, in a collapsed state device 40 is a generally thinmember and may be introduced through smaller channels within thevertebra. The device may be deployed or expanded within the vertebra bydisplacing or pushing the anterior end plate 46 in an outward directionand creating a vertical force that displaces upper and lower plates 42,44 away from each other to thereby reduce a vertebral compressionfracture. Ratchet grooves 50 prevent movement of free end 52 of anteriorplate 46 in an opposite inward direction and further facilitatesdistraction and support of a bone fracture as the anterior end plate 46is rotated or pushed outward. As shown in FIG. 3, in an expanded state,device 40 generally resembles a box or parallelogram. In one embodiment,an insertion tool 54 may be removably attached to a posterior portion ofdevice 40 and a pusher rod 56 or similar device may be advanced in ananterior direction 55 to push or force anterior end plate 46 outward inthe anterior direction. In another variation, a flexible joint orlinkage may be provided adjacent the posterior portion of device 40 tofacilitate insertion and advancement of pusher rod 56. According to oneaspect of this embodiment, a portal or opening 58 may be providedthrough posterior plate 48 to facilitate attachment of insertion tool 54and provide a passage through which bone cement or other filler materialmay be inserted into the interior of the device.

According to one embodiment of a method of treating bone according tothe invention, a bone treatment device, such as device 40 describedabove, may be introduced into a damaged vertebral body by first makingone or more fairly small incisions in the tissue of a patient. Followingthat, an opening may be formed in the vertebral body by means ofwell-known and frequently used instruments. In one variation an openingmay be made via the pedicle which connects the rear part of the vertebrato the vertebral body and the bone treatment device or implant may beinserted into a vertebral body through a minimally invasive proceduresuch as through a small diameter portal.

For example, in the embodiment of FIGS. 3-5, device 40 may be insertedin a first or collapsed condition, as shown in FIG. 4, the instrument ispushed into the bone portion through the aforesaid opening (not shown)in its collapsed position by means of an auxiliary insertion tool 54 andplaced into the vertebral cavity 18. Subsequently, the device 40 may beexpanded within the vertebral cavity as described above until thatexpansion is complete and the bone treatment device may be fixated inthe extended condition. In addition, the insertion tool 54 may then bedisconnected from the device. If the surgeon should decide just beforethe fixation stage that the implant is not correctly positioned in thevertebral cavity, he may collapse the device again and withdraw itthrough the aforesaid openings.

In the extended or expanded position, the bone treatment device 40 isgenerally configured and dimensioned to stretch the vertebrasubstantially to its original dimension, as it were. In the extended orexpanded condition the inserted device or implant may take up loads thatare exerted on the vertebra. The space formed within the vertebra maythen be filled with a filler material or other therapeutic materialwhich may stimulate bone growth as described above.

Referring to FIG. 6, another embodiment of a bone fracture distractiondevice 60 is shown. Device 60 is generally similar to device 40described above except the posterior plate is removed and the upper andlower plates 42, 44 are directly hingedly or linkedly attached at aposterior end 67. In operation, device 60 may be ratchetedly advancedsimilar to device 40 described above, however, in an expanded stateddevice 60 resembles a triangle. According to one embodiment, bone growthmedia and/or bone cement may be inserted or injected into device 40 topermanently lock into place or allow bone to grow through implant.

The materials used in constructing devices 40, 60, and the other devicesdescribed below may comprise any of a wide variety of biocompatiblematerials. In certain embodiments, a radiopaque material, such as metal(e.g., stainless steel, titanium alloys, or cobalt alloys) or a polymer(e.g., ultra high molecular weight polyethylene) may be used, as is wellknown in the art. In alternate embodiments, a radiolucent material, suchas polyetheretherketone (PEEK) may be used. Polymethylmethacrylate(PMMA) can also be used. In other alternate embodiments, a generallyporous or microsphere material may be used. Exemplary microspherematerial that may be used is disclosed in U.S. patent application Ser.No. 11/552,255, filed Oct. 24, 2006 and entitled “Porous and NonporousMaterials for Tissue Grafting and Repair,” the entire contents of whichare incorporated herein by reference.

Referring to FIG. 7, an end view of another embodiment of a bonetreatment device 70 is shown. Device 70 generally comprises a superiorend plate 72 and an inferior end plate 74 telescopingly interconnectedsuch that end plate 72 and end plate 74 may slide apart or separate inthe vertical direction. According to one aspect of this embodiment, armextensions 76 may extend downward from superior plate 72 and upward frominferior plate 74 and arm extensions 76 may be juxtaposed side by sideto permit sliding or telescoping contact therebetween and allow relativevertical movement while generally preventing lateral displacement. Aninterior chamber 78 may be defined interior to arms 76 and end plates72, 74 and a port or opening 79 may be provided to allow access to theinterior chamber from the exterior of device 70. In one variation, thedevice 70 may be deployed or expanded within the vertebra by injecting afiller material into the interior chamber to fill chamber 78 andcreating a vertical force that displaces upper and lower plates 72, 74away from each other to thereby reduce a vertebral compression fracture.The filler material may be liquid, semi-liquid, or any other flowablesubstance or injectable material. Some exemplary substances include, butare not limited to, bone cement such as PMMA, crushed bone, bone pieces,bone matrix, polymers, microsphere materials or combinations thereof. Asdepicted in the end view of FIG. 6, the lateral width 77 of device 70may be between about 4 nml to about 6 tnm. According to one embodiment,end plates 72, 74 may be curved or arcuate when. viewed from the top,while in alternate embodiments, end plates 72, 74 may have a rectangularshape. However, in other embodiments, end plates 72, 74 may have anydesired shape. In another variation, endplates 72, 74 may have convex orconcave profiles when viewed from the side. In one embodiment, plates72, 74 and extensions 76 may be made from resorbable polymer material.In another embodiment, device 70 may be made from a rigid biocompatiblemetal. In yet another embodiment, device 70 may be made from a PEEKmaterial. In one variation, plates 72, 74 may have perforationsextending therethrough to permit the filler to flow or exit therethroughand/or to permit bone to grow through to facilitate fusion.

Referring to FIGS. 8A-8B, another embodiment of a bone treatment device80 is shown in an expanded or extended condition. Device 80 is similarto device 70 described above, except a plurality of telescoping orexpandable vertical segments or regions 82 are provided. Each region 82may comprise another set or pair of arm extensions 76 extending downwardfrom a superior region and upward from an inferior region. Similar todevice 70 described above, extensions 76 may be juxtaposed side by sideto permit sliding or telescoping contact therebetween and allow relativevertical movement while generally prevent lateral displacement. Similarto device 70, an interior chamber 78 may be defined interior to arms 76and end plates 72, 74 and the device may expand or telescope upward wheninterior chamber 78 is filled. In this embodiment, device 80 maygenerally expand or telescope upwards a greater distance than device 70if both devices are provided with the same length extension arms 76. Forexample, in the embodiment of FIG. 7, device 80 may expand or telescopeupwards a total of three times the initial height since there are threetelescoping segments 82. In alternate embodiments, more than threevertical telescoping segments may be provided. In yet anotherembodiment, one or more lateral telescoping segments may be provided inaddition to the vertical telescoping segments.

Referring to FIGS. 9-11 an alternate embodiment of a bone treatmentdevice 90 is shown. Bone treatment device 90 generally comprises acollapsible box-like frame member having upper and lower plates 92, 94and posterior and anterior support legs 96, 98. According to one aspectof the embodiment, device 90 may be molded from a polymer material suchas PEEK and may have thin walled or weakened corner sections 95 suchthat device 90 may be collapsed or flattened. In this regard, device 90may be inserted into a vertebral body in a collapsed condition asgenerally shown in FIG. 9 and a plunger 97 may be removably attached toan interior portion of a distal or anterior support leg 98. In onevariation, the device 90 may be deployed or expanded within the vertebraby may be pulled backward in the direction of arrow 99 to force the boxto come together, as shown in FIG. 10, and creating a vertical forcethat displaces upper and lower plates 92) 94 away from each other tothereby reduce a vertebral compression fracture. In one variation,device 90 may be molded such that it is biased to maintain its boxlikeshape so that it in operation it snaps together. As shown in FIG. 10, inan expanded condition, device 90 defines an interior chamber 101. Asdescribed above with respect to previous embodiments, chamber 101 may befilled with a filler material such as bone cement or other similarmaterial to facilitate bone growth and/or fusion. In this regard,plunger 97 may be provided with a plurality of perforations or holes 104to deliver bone cement therethrough to chamber 101. Referring to FIG.11, a gun or triggered device 102 may be attached to the proximal end ofplunger 97 to deliver bone cement therethrough under pressure.

Referring to FIGS. 12A-B, another embodiment of a bone fracturetreatment device 120 is shown. As seen in the side view of FIG. 12A,treatment device 120 generally comprises upper and lower rigid endplates 122, 124 configured and dimensioned to receive a threaded insertmember 126 therebetween. In one variation, the threaded insert member126 may have a generally tapered profile and may be similar to, forexample, a pipe thread. In another variation, threaded insert 126 mayhave a generally straight profile. In one variation, the superior andinferior surfaces of plates 122, 124 may be maintained at leastinitially in a generally parallel relation. The interior sides orsurfaces 123, 125 of plates 122, 124 may be tapered lengthwise with awider initial separation between plates 122, 124 adjacent the posteriorside of device 120 and a narrower separation adjacent an anterior side.As shown in the end view of FIG. 12B, plates 122, 124 may have opposedsemi-circular shaped notches, grooves, or troughs 128 disposed along theinterior portion thereof. In one variation, plates 122, 124 may beconstrained laterally such that notches 128 remain generally verticallyaligned. In certain embodiments, notches 128 may be threaded to receivethe threaded insert member 126. The device may be deployed or expandedwithin the vertebra by inserting the threaded insert member 126 betweenend plates 122, 124. Because the interior of end plates 122, 124 istapered, as the threaded insert member is inserted or threadedlyadvanced from the posterior end to the anterior end, device 120 mayexpand in the superior-inferior direction and create a vertical forcethat displaces upper and lower plates 122, 124 away from each other tothereby reduce a vertebral compression fracture. Referring to FIG. 12C,an alternate embodiment of a bone treatment device 129 may be providedthat is generally similar to device 120 except device 129 may beexpanded by drawing backward insert member 126 in the posteriordirection.

Referring to FIG. 13A, another embodiment of a bone fracture treatmentdevice 130 is shown. Device 130 generally comprises rigid superior andinferior plates 132, 134 interconnected by expandable posterior andanterior walls 136, 138. In this embodiment, a central expansion screw140 may extend through nuts 142, 144 on opposite ends of device 130.Nuts 142, 144 may be rotatably connected to a central portion of walls136, 138. In this regard, plates 136, 138 may comprise generally rigidbar members or linkages 146 that are rotatably connected to nuts 142,144. The device may be deployed or expanded within the vertebra byrotating central expansion screw 140 to draw nuts 142, 144 together.When nuts 142, 144 are drawn together, superior and inferior plates 132,134 may distract, separate apart) or expand in the superior-inferiordirection and create a vertical force to thereby reduce a vertebralcompression fracture. In an alternate embodiment, shown in FIG. 13B, analternative device 147 may have a ratcheting ring 148 disposed over aserrated shaft 149 and device 147 may be expanded by linearly advancingshaft 149 with respect to rings 148.

Referring to FIG. 14, another bone treatment device 150 is shown. Device150 is similar to device 130 described above, except a scissor jack-likemechanism 151 may be used to move the upper and lower plates 152, 154apart and move device 150 to its expanded position.

Referring to FIGS. 15A-C, an alternate embodiment of a bone treatmentdevice 160 is shown. Device 160 generally comprises a spring loadedassembly with an upper portion 162 and a lower portion 164. As shown inFIG. 15A, device 160 may have an elongate structure extending along alongitudinal axis 163 from a posterior end 165 to an anterior end 167.As shown in FIG. 15C one or more biasing members or compression springs166 may be disposed between upper and lower portion 162, 164 to bias theupper and lower portions apart. In an alternate embodiment, one or moreleaf springs may be disposed between upper and lower portions 162, 164.One or more flexible bands may be disposed on or around the exterior ofdevice 160 to prevent the device from coming apart. As with previouslydescribed embodiments, device 160 may be inserted into a vertebral bodythrough a minimally invasive procedure such as through a small diameterportal. Once device 160 exits the portal into the interior portion ofthe vertebral body, the upper and lower portions 162, 164 are biasedapart and creating a vertical force that displaces upper and lowerplates 162, 164 away from each other to thereby reduce a vertebralcompression fracture.

Referring to FIGS. 16A-B, another embodiment of a bone treatment device170 is shown. Device 170 generally comprises an upper support 172 and alower support 174 threadably interconnected thereto. Device 170 may bethreadably expanded by, for example, a gear mechanism 175 accessible onan exterior portion of device 170 and actuatable through an insertiontool 176. Exemplary threaded interconnection mechanisms, gearmechanisms, and actuation mechanism useable with device 170 is discussedin U.S. patent application Ser. Nos. 11/110,844 and 11/464,625, filedApr. 21, 2005 and Aug. 15, 2006, respectively, and both entitled“Expandable Vertebral Prosthesis,” the entire contents of which areincorporated herein by reference. As shown in FIG. 16A, device 170 maybe pivoted after insertion into a vertebral body such that that device170 may turn from an initial alignment along the pedicle to a morevertical orientation as shown in FIG. 16B.

Referring to FIG. 17, another embodiment of a bone fracture treatment180 device is shown. Device 180 generally comprises an outer wallmembrane or sack 182 enclosing a central region 184. In one variation,outer wall membrane 182 is made from a generally flexible yet resilientmaterial, including, but not limited to, cloth, mesh any or otherflexible elastic plastic or synthetic material, such as polyurethane.Any biocompatible material may be used that has the ability to beinserted in a cannulated tube and inserted in the vertebral body. Oncein the vertebral body, the material should be able to be filled with amaterial to stretch the material outward to cause distraction of the endplates. Wall membrane 182 may have one or more openings or perforationsextending through the wall from the exterior to the central region 184.In one embodiment, an expandable sponge-like, absorbent, or memory foammember 186 may be positioned in the central region 184 and may be housedor enclosed by wall membrane 182. The device may be deployed or expandedwithin the vertebra by activating the foam member 186 to triggerexpansion thereof to create a vertical or expansive force to therebyreduce a vertebral compression fracture. In one variation, the expansionof foam member 186 may be triggered by exposure to elevated temperaturesor fluids such as, for example} water or body fluid. Such exposure maybe assisted by injecting the fluid through the wall membrane 182 orthrough a predefined connection. In alternate embodiments, a hardeningfiller material such as bone cement may be injected into foam member 186to trigger expansion and the cement may harden thereafter with foammember 186 in an expanded state. In certain embodiments, wall membrane182 may be defined with a limited flexibility such that it may expand toenclose a maximum volume of the central region 184 and preventoverexpansion of foam member 186. In this regard, wall membrane 182 maybe designed and configured to expand to conform to the interior volumeof an intact healthy vertebral body of a particular patient as desiredor diagnosed by a practitioner user.

Referring to FIG. 18, another embodiment of a bone treatment device 190is shown. Device 190 is similar to device 180 described above, exceptthe membrane 182 may be filled with a porous filler material 192 such asa microsphere material Exemplary microsphere material that may be usedwith device 190 is disclosed in U.S. patent application Ser. No.11/552,244, filed Oct. 24, 2006 and entitled “Porous and NonporousMaterials for Tissue Grafting and Repair,” the entire contents of whichare incorporated herein by reference. The device may be deployed orexpanded within the vertebra by inserting or injecting a plurality ofmicrosphere members to trigger expansion of device 190 to create avertical or expansive force to thereby reduce a vertebral compressionfracture.

Referring to FIGS. 19A-B, another embodiment of a bone fracturetreatment 200 device is shown. Device 200 generally comprises aplurality of elongate bands or strips 202 having a generally arcuateshape extending along a longitudinal axis 204 from a posterior end 206to and anterior end 208. Bands 202 are pinned or fixed together at theposterior and anterior ends 206, 208 and are generally spaced radiallyabout axis 204. According to one embodiment, device 200 may alter itsshape from, for example, a collapsed elongate tubular structure having afirst diameter or maximum height measured transverse to axis 204 to ageneral ovoid shaped or partially spherical shaped scaffold having asecond larger diameter or maximum height measured transverse to axis204. In one variation, bands 202 may be made from a generally flexibleyet resilient material, including, but not limited to, nitinol,titanium, stainless steel, PEEK, any or other flexible biocompatiblematerial It could also be made from memory alloy that resumes apredefined shape when exposed to heat or other triggering methods. Inone variation device 200 may have a central rod 132 to facilitateinsertion and expansion thereof in-situ.

Referring to FIGS. 20A-B, cross-sectional views of another embodiment ofa bone treatment device 220 is shown. Device 220 generally comprises aplurality of elongate finger members 222 extending along a centrallongitudinal axis 224. In one variation, fingers 222 may be made from agenerally flexible yet resilient material, including, but not limitedto, nitinol, titanium, stainless steel, PEEK, any or other flexiblebiocompatible material. Fingers 222 could also be made from memory alloythat resumes a predefined shape when exposed to heat or other triggeringmethods. The free ends 226 of fingers 222 may be biased outward suchthat when fingers 222 are pushed outward beyond the end of a tubularportal free ends 226 flare or expand outward. In this regard, as shownin FIG. 20B, the distal ends 226 of the fingers 222 may extend laterallybeyond the wall of the portal tube or delivery cannula and may be usedto create a cavity within the vertebral body. In one variation, thedevice 220 may be deployed or expanded within the vertebra when pushedbeyond the end of the working cannula to create a vertical force toreduce a vertebral compression fracture. 111 certain embodiments, theremay be a plurality of fingers 222 radially disposed about axis 224. Inone embodiment, at least four fingers are provided. In anotherembodiment, the fingers may be semi-tubular and each finger 222 maycomprise one fourth of a portion of a cylinder.

Referring to FIG. 21, another embodiment of a bone treatment device 230is shown. Device 230 generally comprises a coil spring body 232. In onevariation, spring body 232 may be made from a generally flexible yetresilient material, including, but not limited to, nitinol, titanium,stainless steel, PEEK, any or other flexible biocompatible material.Spring body 232 could also be made from memory alloy that resumes apredefined shape when exposed to heat or other triggering mechanisms. Inone embodiment, a foot or tab 234 may extend from one end of body 232 togrip, engage, catch onto or otherwise contact a bone portion of avertebral body, such as an end plate. Spring body 232 may be configuredand dimensioned to be biased outward. In one variation, the device 230may be deployed or expanded within the vertebra by rotating or uncoilingthe spring to create a vertical force to thereby reduce a vertebralcompression fracture. Similar to many of the embodiments describedabove, device 230 may inserted in a minimally invasive procedure intothe vertebral body such as, for example, through a working cannulaextending through the pedicle. In one variation, spring body 232 may beany kind of coiled band. In one variation, spring 232 could be a flatspring that coils out like a rolled up sheet of paper. In one variation,the inner part or central portion of spring body 232 may include a oneway ratchet mechanism which would allow expansion and preventcontraction of spring body 232.

Referring to FIGS. 22A-B, another embodiment of a bone treatment device240 is shown. Device 240 generally comprises a plurality of plates orfolded plates or folded bands 242. In one variation, bands 242 may bemade from a generally flexible yet resilient material, including, butnot limited to, nitinol, titanium, stainless steel, PEEK, any or otherflexible biocompatible material. Plates 242 could also be made frommemory alloy that resumes a predefined shape when exposed to heat orother triggering methods. Bands 242 may be forcibly advanced into aninterior of a vertebral body through a minimally invasive technique suchas through a working cannula as shown in FIG. 22A and packed into theinterior of a vertebral body from the anterior portion to the posteriorportion. As best seen in FIG. 22A, bands 242 may be thin wafer likemembers that are flexible enough to be folded or curved to fit down acannula, yet resilient enough to reform or spring back to a morestraightened shape once inserted into the vertebral body. Once a desiredamount of bands 242 are inserted into the vertebral body a final orposterior most piece 244 may be inserted into the vertebral body. In onevariation, piece 244 has a general wedge shape to facilitate the packingof bands 242 within the vertebral body and transfer lateral force thebands to trigger cause the bands to expand in a vertical direction andcreate a vertical or expansive force to thereby reduce a vertebralcompression fracture. Wedge piece 244 may also function to lock thebands in place or keep the assembly together. As with previousembodiments, device 240 may be used in a minimally invasive procedureand in one embodiment bands 242 may be fed down a tube or portal 244, asshown in FIG. 22A. In one variation bands 242 may be fed along aguidewire so the bands 242 may have a central hole to accommodate theguidewire.

Referring to FIGS. 23A-B, an embodiment of a cavity creation tool 250 isshown. Cavity tool 250 generally comprises a plurality of bars or legs252 rotatably interlinked. According to one variation, at least threebars 252 may be interlinked. In operation, device 250 may insertedthrough a cannula 254 into a vertebral body with legs 252 in a collapsedcondition and once inserted into the vertebral body the legs 252 may bemanipulated to expand outward and rotated an moved about within thevertebral body to excavate or break up the cancellous bone within thevertebral body.

Referring to FIG. 24A-B, another cavity creation tool 260 is shown. Tool260 generally includes a plurality of L shaped fingers 262 rotatablyconnected to an exterior portion of a tubular member 264. Finger 262 maybe moved from a retracted position, shown in FIG. 24A, to facilitateinsertion of tool 260 through a working cannula 266 to an extendedposition, as shown in FIG. 24B, to facilitate excavation of cancellousbone from the interior of a vertebral body. Similar to tool 250described above, tool 260 may be rotated and manipulated within thevertebral body to break up the interior cancellous bone of the vertebralbody to, among other things, create a cavity to receive a bone treatmentdevice. For example, referring to FIG. 25, another exemplary bonetreatment device 280 that may be inserted into such a cavity is shown.Device 280 generally comprises a sponge or sponge-like member that maybe filled with bone cement or bone matrix.

While it is apparent that the invention disclosed herein is wellcalculated to fulfill the objects stated above, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art.

What is claimed is:
 1. A cavity creation instrument comprising: acannula having a proximal end and a distal end; and one or more cavitycreation elements extendable from the cannula, the one or more cavitycreation elements including a superior plate and an inferior platedisposed along a vertical axis, wherein the one or more cavity creationelements include a first low-profile configuration and a second expandedconfiguration in which the one or more cavity creation elements extendaway from a body of the cannula to facilitate excavation of cancellousbone from an interior of a vertebral body and create a cavity, whereinthe one or more cavity creation elements are coupled to a rotatingexpansion screw, wherein when the rotating expansion screw is actuatedin a first direction, the one or more cavity creation elements extendaway from the body and the superior plate and the inferior plateseparate away from one another along the vertical axis and when therotating expansion screw is actuated in a second direction, the one ormore cavity creation elements extend toward the body and the superiorplate and the inferior plate move toward one another along the verticalaxis.
 2. The instrument of claim 1, wherein the one or more cavitycreation elements comprise bar members.
 3. The instrument of claim 2,wherein the bar members are insertable within the cannula.
 4. Theinstrument of claim 2, further comprising at least two bar membersrotatably interlinked.
 5. The instrument of claim 1, wherein the one ormore cavity creation elements comprise L-shaped fingers.
 6. Theinstrument of claim 5, wherein the instrument comprises at least twoL-shaped fingers rotatably interlinked.
 7. The instrument of claim 5,wherein the fingers are connected to an exterior of the cannula.
 8. Acavity creation instrument comprising: a cannula having a proximal endand a distal end; and a superior plate and an inferior plate disposedalong a vertical axis, and two or more bar members extendable outwardlyfrom a distal end of the cannula, wherein the bar members include afirst collapsed configuration such that the bar members are insertablethrough the cannula and a second expanded configuration wherein the twoor more bar members are coupled to a rotating expansion screw, whereinwhen the rotating expansion screw is actuated in a first direction, thetwo or more bar members extend away from the body and the superior plateand the inferior plate separate away from one another along the verticalaxis, and when the rotating expansion screw is actuated in a seconddirection, the two or more bar members extend toward the body and thesuperior plate and the inferior plate move toward one another along thevertical axis.
 9. The instrument of claim 8, wherein the bar members arerotatably interlinked.
 10. The instrument of claim 8, further comprisingat least three bar members rotatably interlinked.
 11. A cavity creationinstrument comprising: a cannula having a proximal end and a distal end;a tubular member; and two or more fingers operably attached to thetubular member, each of the two or more fingers having a first end, asecond end, and a pivot point located between the first and the secondend and rotatably coupled to the tubular member, wherein the fingersinclude a first retracted configuration whereby the fingers are orientedsuch that their bodies are substantially aligned with a body of thecannula and a second expanded configuration whereby the fingers extendoutwardly to facilitate excavation of cancellous bone from an interiorof a vertebral body and create a cavity, wherein the two are morefingers are coupled to a rotating expansion screw, wherein when therotating expansion screw is actuated in a first direction, the two ormore fingers extend away from the body and the first ends of the two ormore fingers extend outside the tubular member and the second ends ofthe two or more fingers are positioned inside the tubular member, andwhen the rotating expansion screw is actuated in a second direction, thetwo or more fingers extend toward the body.
 12. The instrument of claim11, wherein the fingers are L-shaped.
 13. The instrument of claim 11,wherein the fingers are rotatable.
 14. The instrument of claim 11,wherein the fingers are independent and not connected to one another.15. The instrument of claim 1, wherein the superior plate and theinferior plate each comprise planar surfaces for contacting thevertebral body.
 16. The instrument of claim 1, wherein one or more nutsare positioned along the rotating expansion screw such that theinstrument is expandable within the vertebral body by rotating therotating expansion screw thereby displacing the superior and inferiorplates along the vertical axis.
 17. The instrument of claim 11, whereinthe tubular member has an exterior portion and the two or more fingersare rotatably connected to the exterior portion of the tubular member.18. The instrument of claim 11, wherein the tubular member having afirst lateral side and a second lateral side and at least one of the twoor more fingers is attached to the first lateral side and at leastanother of the two or more fingers is attached to the second lateralside.